CAT's FK/IK rig-manipulation system lets you simply push and pull the rig parts into the pose you want, whether in IK or FK. For walk-cycle sequences, CATMotion allows you to create a fully customized walk cycle and then direct the character around the scene without the need to place individual footsteps. Footprint collision detection provides the icing on the cake.
Animation is created in CAT's non-linear animation (NLA) system, the heart of which is the Layer Manager. One of the big advantages of CAT's NLA system is that you can work directly in an animation layer without having to go back out and tweak the source animation elsewhere.
Image courtesy of Deck13, from the game 'Jack Keane'
CAT uses a layer-based animation system, which means that all keyframes are created in layers. There are two types of layers for keyframe animation: Absolute and Adjustment (relative).
You create new animation in Absolute layers. Absolute layers include CATMotion and absolute (keyframe animation) layers, as well as imported motion data, which you load into an absolute layer.
You can edit existing animation non-destructively with adjustment layers in the Layer Manager. Animation that can be affected with adjustment layers includes CATMotion, absolute keyframe animation, motion capture data, and even other adjustment layers.
The goal of the inverse kinematics system in CAT, called FK-driven IK, is to let you interact with your character rig intuitively, without having to think too much about IK and FK at all.
To allow a bone to stretch during animation, select, go to the Hierarchy panel, click Link Info, and in the Animation Mode group, turn on Manipulation Causes Stretching. This feature lets you create bounce-and-stretch animation interactively in the viewport simply by moving the rig elements around.
CAT's animation layering system has been a fundamental part of the software since day one. All layer management is performed using a simple rollout called the Layer Manager (CAT).
The FK/IK system in CAT lets you simply push your character into the pose you want without having to worry about the too much about IK and FK. Most of the control you'd normally associate with IK is also present in FK as well and vice-versa.
CAT provides dedicated IK controls for animating parts of the rig, including limbs, hands and fingers, feet, and hubs. This section includes descriptions of these controls.
The retargeting system in CAT, available on all limbs, attempts to maintain the IK solution and the angles of the limb bones by pushing out or pulling in and rotating the hub. This is in contrast to a conventional IK system, which leaves the root object (hub) in place and moves the IK target only without taking into account the angle of the limb bones.
As with most types of animation in 3ds Max, animation keys in CAT are stored in Track View. To access the keys for an element in a CATRig, simply navigate to the element in Track View.
